2D/3D interface engineering: direct Z-scheme g-C₃N₄/YMnO₃ heterojunction for reinforced visible-light photocatalytic oxidation

Graphitic carbon nitride (g-C₃N₄) is a two-dimensional (2D) photocatalyst, but it appears a mediocre catalytic property due to the recombination of charge carriers. Constructing heterojunctions can boost the separation and suppress the recombination of photo-generated electron–hole pairs. For the conventional Type-II heterojunction, the oxidation ability is significantly reduced due to the decreasing of band gap. We try to maintain its oxidation capacity and promote the artificial bandgap by tailoring a Z-scheme heterojunction through interface engineering. Herein, we grafted different proportions of YMnO₃ 3D-nanoparticles onto g-C₃N₄ 2D-nanosheets. This special 2D/3D mixed-dimensional nanocomposite exhibits efficient charge carrier transport performance according to the electrochemistry and photocurrent measurement. The outstanding photocatalytic oxidation ability can be verified by the rate of Rhodamine B degradation, which is 3.8 and 2.3 times of YMnO₃ and g-C₃N₄, respectively. Theoretical calculation, active group capture experiments and electron spin resonance indicate the energy band position and the reactive groups (superoxide radicals and holes). The optimized g-C₃N₄/YMnO₃ heterojunction utilizes the interfacial synergistic effect to achieve a composition of vigorous oxidizing ability and outstanding visible light harvesting. This work will pave a promising access for mechanism and interface engineering of other g-C₃N₄-based Z-scheme heterojunctions.